The Clinical Research Center for Periodontal Disease, 02 year, will conduct studies in three major project areas: 1) The Microbiological Studies Section will continue to define and describe the bacterial flora of defined periodontal disease states, with concentration of effort on moderate periodontitis and juvenile periodontitis. 2) The Immunological Studies Section will identify oral bacteria which contain B-cell polyclonal activators (PBAs), study the nature of PBAs, determine if clinical treatment of severe periodontitis alters responsiveness to PBAs, and extend studies of responsiveness to PBAs to subjects with periodontal disease groups not studied previously in this regard. Methodolgy for freeze-storage of lymphocytes will continue to be developed. 3) The PMN Function Section will continue to study polymorphonuclear leukocyte (PMN) dysfunction in juvenile periodontitis, and compare results to other periodontal disease groups. The screening test for dysfunction is a chemotaxis assay. The bases for dysfunction will be probed by analysis of chemo-attractant-perturbed cyclic nucleotide levels and calcium flux. This section will also search for bacterially produced ligands of peptide PMN-chemoattractants, attempt to purify them, and assess their biologic activity. Clinical investigators will identify and evaluate periodontal status of appropriate subjects, and with assistance from biostatisticians, continue to analyze periodontal disease(s) in view of laboratory findings.